I hacked up my 10' of 1/2" PVC the other night and pieced together a closed loop. I currently have a mag 7 driving it. The pump is outside the tank.

After hearing so many folks say that they don't even bother gluing their PVC pieces together, I dry fit it all together and turned it on. After getting it primed it worked quite well, except I was getting a ton of micro fine bubbles coming from the outlets. I put the prefilter that came with the Mag7 on the intake pipe and the bubbles are so tiny the water looks milky as it comes out of the pipes.

Is this an air leak in the intake pipe or is there something else going on?